Diversification of energy supply has been on progress. As one of the energy supply systems, wind turbine generation using natural energy has been known from ancient times. As wind turbines, vertical axis type wind turbines and horizontal axis wind turbines are known. Many of the vertical axis type wind turbines are small type wind turbines, in which a Darrieus type wind turbine and a straight blade vertical axis type wind turbine are known. In the horizontal axis wind turbines suitable for a large scale of power generation, a three-blade type wind turbine is a mainstream.
As the three-blade type wind turbine stated above, a large-sized wind turbine with the diameter of 60 m and more between a blade end and an opposite blade end in a rotation state is on a practical operation. A wind turbine power generation apparatus includes a wind turbine tower which is higher than the radius length of the blade, a nacelle rotatably installed at the top of the wind turbine tower, and a three-blade assembly rotatably installed to the nacelle. The three-blade assembly includes a rotor head rotatably supported by the nacelle, and three rotating blades installed to the rotor head in a pitch angle adjustable manner. When the three-blade assembly is installed to the nacelle, climbing cranes are employed for the wind turbine tower so that the wind turbine tower is built up from the ground to the height direction successively, as disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 10-205429). The climbing cranes are also used for suspending the three blades.
The mass of the three-blade assembly exceeding 60 m is huge. It is important for suppression of the increase of the construction cost to suspend the three-blade assembly which was integrally assembled, rather than to suspend each one of the three blades. In the suspension of the three-blade assembly, suppression of the rotational movement around the center of gravity and installation of a rotation plane formed by the three blades on a substantially vertical plane are required in order to avoid damages caused by contacts between the three-blade assembly and the wind turbine tower and to provide operational safety.
A conventional construction method includes a manual operation for suspending a suspension technique such as a nylon sling to blades and a head in suspending the three-blade assembly by a crane. A slinging operation is conducted by a slinging skilled worker for sling work in a high place and a skilled work including an operation of adjusting the center of gravity. Accordingly, suspension to eliminate the skilled work as much as possible is required.
A construction method of a wind turbine power generation apparatus related to the above carried-out is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 10-205428). In this conventional example, the climbing crane is used. However blades are installed to the nacelle. Similar techniques are disclosed in Japanese Laid Open Patent Applications (JP-A-Heisei 10-205429, JP-A-Heisei 10-205430, and JP-A-Heisei 11-82285).